CHICAGO – Thanks to convoluted terminology, not to mention confusion in the literature, physicians have been known to frequently misdiagnose vascular malformations as hemangiomas, but an evolving understanding of their differences may lead to more precise diagnoses, according to a report at a symposium on vascular surgery sponsored by Northwestern University.

“Historically there has been a great deal of confusion in the literature when it comes to the nomenclature used to describe vascular anomalies,” said Naiem Nassiri, MD, of Robert Wood Johnson Medical School, New Brunswick, N.J. He pointed out that the term hemangioma “or derivatives thereof” – cavernous hemangioma, cavernous angioma, lymphangioma and cystic hygroma – are “absolute misnomers and continue to be misused and applied almost haphazardly to any anomalous vascular lesion.”

He cited reports that 71% of vascular anomalies have been improperly called hemangiomas, 69% have initially been diagnosed incorrectly, and 21% received the wrong treatment (Pediatr Dermatol. 2008;25[1]:7-12; Plast Reconstr Surg. 2011:127[1]:347-51). “Erroneous terminology has prognostic as well as diagnostic and therapeutic implications, and these can actually be quite devastating for the patient, not only clinically and physically but psychologically as well,” Dr. Nassiri said.

Using the International Society for the Study of Vascular Anomalies classification for hemangiomas and vascular malformations can help physicians make the differential diagnosis, Dr. Nassiri said. Hemangiomas are neoplastic lesions of infancy, though not always congenital, with a finite growth phase, whereas vascular malformations (VMs) are nonneoplastic, congenital lesions that can appear at any age and do not regress spontaneously, he said.

Infantile hemangiomas typically appear as the classic strawberry birthmark in children, whereas VMs tend to appear later in life. “They require some environmental trigger, such as trauma, activity, or changes in the hormonal milieu to manifest onset,” he said of VMs.

Simply put, VMs fall into three broad categories: slow-flow malformations, which include lymphatic and venous malformations; high-flow arteriovenous malformations (AVMs) and fistulas; and congenital mixed syndromes, which can include combinations thereof.

Dr. Nassiri noted that contrast-enhanced MRI is the standard imaging modality for diagnosis of VMs, and can differentiate between slow-flow and high-flow lesions. However, vascular specialists must be vigilant in ordering imaging for slow-flow lesions. “Orders can be changed to MR venography, and I’ve had patients who’ve gone decades with multiple MR venograms and no one can figure out what’s going on as no identifiable lesion is readily detected,” he said. “MR venograms are fantastic for detecting truncular blood flow where there typically are no anomalies in the vast majority of patients with isolated venous malformations, but on contrast-enhanced MRI these convoluted cluster of anomalous veins light up like Christmas trees.”

Lymphatic malformations affect the head and neck more so than the extremities, trunk or viscera, and are prone to infection and bleeding. “You can think of these as fluid-filled balloons, and the goal of treatment is fairly simple: You want to puncture the balloon and drain the fluid inside so as to obtain maximum wall collapse,” Dr. Nassiri said. Infusion of a sclerosant causes an inflammatory reaction leading to fibrosis, which then prevents balloon re-expansion. Surgical excision is best used as a secondary adjunct.

Venous malformations, comprising about 80% of all VMs, typically present as soft, spongy blue or purple compressible masses with associated pain that worsens with exertion, Dr. Nassiri said. “The most dangerous thing that is often overlooked, even by some of the physicians that treat these on a regular basis, is localized intravascular coagulopathy, which if left untreated can progress to fulminant disseminated intravascular coagulopathy,” he said. This tends to occur more in the more widespread varieties of venous malformations.

A common misnomer associated with venous malformations in adults is “liver hemangioma,” owing to the confusing nomenclature, Dr. Nassiri said. “When interrogated angiographically,” he said, “what is often labeled as a hepatic hemangioma is in fact a venous malformation. Natural history of the two entities is completely different.”

Dr. Nassiri described congenital high-flow AVMs as “convoluted networks of blood vessels with poorly differentiated endothelial cells that have neither a venous nor an arterial designation; this entity, otherwise known as a nidus, sits between the feeding arteries and the draining veins.” Treatment aims to eliminate the flow within that nidus.

Super-selective microcatheterization is the best option for nidus access and embolization using liquid embolic agents, preferably those that polymerize when infused. “This is probably the most potent angiogenic entity I’ve ever seen,” Dr. Nassiri said of the nidus.

“It’s like a low-pressure sump and it will recruit collaterals vigorously, so you have to eliminate that nidus.” A variety of different embolic agents, some off label, may be used for high flow AVMs.

For congenital mixed syndromes, the same diagnostic and therapeutic concepts hold true depending on the type of VM involved. Dr. Nassiri advised a multidisciplinary approach, and noted that early trials have investigated the use of sirolimus in severe, life-threatening cases (Br J Clin Pharmacol. 2016;82[5]:1171-9. doi: 10.1111/bcp.13022).

Dr. Nassiri disclosed serving on the speakers bureaus for Boston Scientific, Penumbra, and Merritt Medical, and is a consultant to Merritt Medical.

Vascular anomalies often misdiagnosed amidst confusion